NASA launched an unmanned test rocket on Wednesday in the hopes it will become the backbone of a new program to send astronauts to the moon and Mars. The Ares program aims to launch with humans onboard by 2015, but budget concerns are threatening its future.

The 100-meter long Ares I-X rocket lifted off and rose 45 kilometers above the Kennedy Space Center in Florida, before falling back to the Earth. Engineers monitored dozens of cameras and onboard sensors as the rocket thundered into the sky.

"Now passing Mach 2 [680.58 meters/second]," said the mission controller. "The vehicle is now 10 miles [16 kilometers] altitude."

As designed, the motors burned for two minutes, then the rocket separated into two segments that fell into the Atlantic Ocean. NASA crews deployed to collect the solid rocket motors for inspection.

Engineers say the launch was a valuable opportunity to study the design and construction of the rocket, which is the first new vehicle to launch at the Kennedy Space Center in nearly 30 years.

Bob Ess directs the Ares I-X test flight team.

"Everything was just how we expected," said Bob Ess. "It was just like the animations we have been showing; it flew at the same speed and the same distance. It just looked much more spectacular in person than it did in planning."

The Ares rocket is a key part of the Constellation program that was announced by President George Bush in 2004. The $60 billion plan was intended to rejuvenate the U.S. space flight program and enable astronauts to return to the moon and eventually land on Mars.

But President Barack Obama has ordered a review of NASA's plans, amid concerns about rising costs. An independent panel has said the current budget will not support the agency's goals, suggesting some missions may need to be dropped.

NASA officials say they will continue advancing work on Constellation until the White House makes a decision on whether to change it.

Constellation program manager Jeff Hanley says the Ares test shows that NASA agency is on the right track.

"We have a design that will do the country service, if it is put into service," said Jeff Hanley. "The performance of the vehicle was very pleasing, to put it mildly."

Current plans call for NASA to end the space shuttle program next year, in part, to help finance development of Constellation. The first manned flight of Ares would not be until at least 2015.

Space agency officials say the break in manned U.S. space flights is unfortunate, but necessary to develop the technology that will carry astronauts into the next generation of space exploration.

"There is definite interest in going beyond low-Earth orbit to discover new things in the solar system," said Doug Cooke. "This is really the first big step we have taken in that direction in a long time."

After the Ares test, Cooke says, one of the next big hurdles is to build the Orion module that will sit atop the rocket and carry astronauts into space.